Data Sheet

VSC7127/VSC7129

Family of Repeater/Retimer and Port

Bypass Circuits for Fibre Channel

G52298-0, Rev 4.3

Page 1

05/01/01

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Features

General Description

urable Repeater/Retimer (CRU) and a Signal Detect Unit (SDU). These parts are typically used in distributing

Fibre Channel signals to an array of disk drives in an FC-AL loop as illustrated in Figure 1. The first

VSC7127’s CRU is configured as a Repeater to attenuate jitter, the second VSC7127’s CRU is bypassed to

reduce power and the third VSC7127’s CRU is configured as a retimer so that the output of the device is a jitter-

compliance point.

Each PBC is a multiplexer that is controlled by the corresponding SELx line which, if HIGH, selects the

external input or, if LOW, selects the output of the previous PBC. For the VSC712xR, when MODE is LOW

and SEL5 is HIGH, the CRU is a sophisticated repeater which has low latency, no peaking and attenuates jitter

even at low frequencies. When MODE is HIGH and SEL5 is HIGH, the CRU is a retimer which eliminates jit-

ter transfer but has increased latency due to an elasticity buffer which adds/drops Fibre Channel fill words in

order to accomodate the difference between the baud rate of the incoming data and the local REFCLK. When

SEL5 is LOW, the CRU is bypassed and powered down. The SDU monitors the analog levels of the IO+/- input

and monitors the output of the CRU digitally to indicate whether valid data is present.

VSC7127/VSC7129 Block Diagram

• ANSI X3T11 Fibre Channel Compliant

• 1.0625Gb/s Operation

Recovery Unit (CRU): Repeater, Retimer or

Bypassed

• Six Port Bypass Circuits (PBC)

•

Analog/Digital Signal Detect (SDU)

• On-Chip Transmit Termination

•

3.3V, 700mW Power Dissipation

• Compatible with HDMP-0451 (VSC7127) or

HDMP-0452 (VSC7129)

• 44-Pin, 10mm PQFP Package

1

0

PBC1

REFCLK

SDU

CRU

1

0

PBC2

1

0

PBC3

1

0

PBC4

CMU

SIGDET

0.1uF

MODE

1

0

PBC0

106.25MHz

0

1

PBC5

SEL5